Application of drilling fluids



Patented Nov. 28, 1950 ornce APPLICATION OF DRILLING Ernst A. Hauser, Cambridge, Mass.

No Drawing. Application January 16, 1948, Serial No. 2,821

V 1 a This invention relates to welldrilling fluids, and more particularly as employed in the drilling of oil and gas wells, by the rotary system of drilling. This, application is a continuation-inpart of application Serial No. 473,969, now abandoned, filed January 29, 1943.

In the drilling of wells, particularly oil and gas wells, under the rotary system of drilling, a

drilling fluid or mud is employed. This drilling fluid when of the water-base type, is either made up from clays obtainable at the well or by the employment of various hydrophilic colloids as described in the Harth Patent No. 1,991,637.

6 Claims. (Cl. 2528.5)

These colloids, of which bentonite is the most important one, hydrate in water, so as to form the drilling fluid. In the drilling of oil wells, oil-base drilling fluids are also employed in which the external or continuous phase is oil instead of water. Such oil base drilling fluids are useful in "drilling in." that is, where the drilling is into the oilor gasbearing stratum, because oil will not fdrown cut" oil or gas as is the case with water. It is also advantageous to employ such oil-base drilling fluids in drilling through shaley formations, which are subject to hydration by water. It is also useful for employment in taking cores. The external phase of the drilling fluid is any suitable oil such as petroleum crude oil, distillate or residue, or a coal tar distillate or residue: oils which are generally employed are kerosene, fuel oil and Diesel oil. However, oil base drilling fluids are not entirely satisfactory, because of a limitation of the character of the solid material heretofore employed. I

One 01' the objects of this invention, therefore, is to provide a well-drilling fluid and a process of drilling wells in which the external phase of the fluid is an oil, which has improved properties, characteristics, and 'modesof operation.

Further objects will appear from the detail description in which will be set forth a number of embodiments of this invention. It is to be understood; however, that this invention is susceptible of various embodiments, and that certain features and subcombinations are of utility and may be employed without referenceto other features and subcombinations, within the scope of the appended claims.

Generally stated, and in accordance with an illustrative embodiment of this-invention, there is employed a material which comprises a cation modified clay which forms a gel in an organic liquid such as the 011 employed, and has a substantial gel characteristic therein. The modified clay is one in which the gel characteristic is exemplified by the fact that two grams of the modified clay swell to at least 12 milliliters in a liquid such as nitrobenzene. In accordance with an illustrative embodiment, the modified clay is one originally exhibiting a substantial base exchange capacity, but in which the cation has been replaced by a substituted cation of the class of onium bases consisting of ammonium, phosphonium, sulfonium, arsonium, stiboni'um, ox-

onium and telluronium bases.

The clays which are useful-as starting materials in accordance with this invention are those exhibiting substantial base-exchange properties,

and particularly those exhibiting comparatively high base-exchange properties and containing cations capable oi. more or less easy replacement. The clays particularly contemplated by the specification and the claims, include the montmorillonites, viz., sodium, potassium, lithium, and other bentonites, viz., Wyoming bentonite, magnesium bentonite (sometimes called hectorite) and saponite; also nontronite, attapulgite, illite, zeolites, and fullers earths, particularly those of the Georgia-Florida type. The base-exchange capacities of the various clays enumerated run from about 15 to about 100, based upon milliequivalents of exchangeable base per 100 grams of clay. More specifically, and in accordance with illustrative embodiments of this invention,

. a clay of the character described and exhibiting substantial base-exchange capacity, is reacted with an organic compound, more particularly one hereinafter generally defined and referred to as an onium compound, by substitution of the clay cation of the organic compound, which cation is. of a class hereinafter referred to as an onium" base; see Hackhs Chemical Dictionary, second edition. This invention is not, however, restricted to the use of a. reaction product of a base-salt with clay-salt, but includes the reaction I product of a free base with an acid-clay.

' A number of the compounds capable of reacting with clays, particularly bentonite, will be described; it is to be understood, however, that various other compounds reactable with clays of the character described, may be employed.

The unmodified clay such as untreated sodium bentonite in contact with water absorbs large quantities of water, and swells, forming a hydrogel. When such a clay is treated with an onium compound, it will cease to swell in water, but will swell in many organic liquids, and will form stable gels and colloidal dispersion. Such swelling 3 characteristic may be determined by introducing 2 grams of the onium-bentonite product in 100 milliliters er nitrobenzene and noting the amount of swelling in cubic centimeters. Thus tonite because of its comparatively high baseexchange capacity, it will be understood that the invention is applicable to onium-clay reaction in the case of amine-bentonite products the emproducts in which the clay is other than benployment of salts of aliphaticamines, including tonite, the propyl, butyl and octylamines containing Exam la 1 from 3 to 8 carbon atoms will not produce an p amine-bentonite product showing a swelling of 2750 g. of a Wyoming bentonitewas dispersed from 5 to 7 ml. in 100 ml. of nitrobenzene. There 10 in 70 liters of water and the slurry allowed to is, however, generally a distinct region of instand for two hours to settle out the non-clay crease of swelling with amine-bentonites in impurities. About 10% of the weight of the which the amine has in excess of 10 carbon bentonite was discarded in this process. 150 g. atoms. Thus the swelling in 100 ml. of nitroben- (2.5 mol) of glacial acetic acid was added to 663 zene of corresponding amine-bentonites are g. (2.5 mol) oi octadecadienylamine and the found to be: decylamine-bentonite (10 carbon amine salt then dissolved in 4 liters of warm waatoms)36 ml.; dodecylamine-bentonlte (12 ter. l 'locculation of the bentonite occurred carbon atoms)-50 ml.; with this high'swelling upon addition of the amine salt solution, and holding through the series, viz., octadecadienylthe fiocculent precipitate was filtered, washed, amine-bentonite (18 carbon atoms)--50 ml., a 20 dried, and pulverized. The resulting bentonite like relation will generally be found for other compound thus obtained may be dispersed in onium-bentonites. Such products may, therevarious organic liquids to form gels. grid-ell be called high-swelling onium-ben E mm p18 u The ratio of the onium compound, such as, 2750 g. of a Wyoming bentonite was dispersed for example, an amine compound to bentonite, in 70 liters of water and the slurry allowed to may be varied within certain limits in convertstand for two hours to settle out the non-clay ing the bentonite to the organophilic condition. impurities. 150 g. (2.5 mol) of glacial acetic In general, it is satisfactory to react the amine acid was added to 464 g. (2.5 mol) of dodecylsalt with the bentonite in the ratio of 100 mil- 3o amine and the amine salt then dissolved in 4 liequivalents of amine salt to 100 grams of benliters of warm water. Fiocculation of the bentonite, which is approximately the base-extonite occurred upon addition of the amine salt change capacity of the standard highly swelling l n. and the precipitate was filtered, sodium bentonltes. Typical values of swelling Washed. dried and pulverized. on the above basis are listed below for a series Example "I of dodecylammonium-bentonites, in which the ratio of amine to bentonite was varied over wide Triphenyl-lauryl phosphonium bromide was limits: prepared by refluxing a mixture of equivalent Aminelbentonite: tomeJlwg. 76 100 126 150 200 sec 8weliln innitrobensene;ml us no use 41.5 no as 15.5

This table indicates the wide range over which weights of triphenyl-phosphine and lauryl brothe amine-bentonite ratio can be varied, but it mide. After six hours the reaction mixture was also shows the optimum eflect exhibited at the cooled and dissolved in alcohol. To a dispertheoretical base-exchange value for this combi-" sion. of g. of Wyoming bentonite in one liter nation. of water was added an alcohol solution of 0.05 For the most'eflicient use of organic base to 50 mol of the phosphonium base. Upon bringing obtain optimum gelling properties, it is therethe pH of'the-slightly basic dispersion to about 4 fore desirable either to select an onium comwith dilute hydrochloric acid, the bentonite pound such as an amine compound, which, when complex fiocculated, was filtered, washed, dried converted to the onium base form and reacted and ground. by base-exchange with. the clay, are absorbed to certain points on the surface of the mineral, Example N a or to substitute the proper aliphatic chain in a One-te ol d do ecrl ethyl mi onium polyammonlum base. V bromide is dispersed in one liter of water, and this The type 1 clay mineral to be used may v ry is then mixed with agitation with 400 c. c. of a with the intended use. For optimumgelling w 56% 89 11 Wyomin! bentonlm. After properties it isbest tov use abentonit'e which exo hou sta d n i s fi t d ed and hibits good gelling properties in water. Howdhe resulting bentonite comp iihfll ever, some non-swelling clays when converted to obtained y be dispersed in Various O an c the onium salt form will swell in organic liquids q and give rise to thixotropi;1 colloidal dispersions. 55 Example V It is to be understood at when reference is made to basic organic onium compounds such The process of ExampleI Viscarried out except that one-tenth moi of decyl-triphenylarsonium as amines, it is implied that before reacting with haudeisused instead or dmodec 1 cm s u o m um the clay by base-exchange, the amine is conbromide verted to the onium form either by the addi- 7o tion of acid or by reason of the fact that some v Example W part of the inorganic base in the naturally oc- Theprocessof Examplelviscarrled out except curring clay consists of hydrogen. that one-tenth mol of decyl-triphenylstibonium Various examples of modified clays embodyhalideisusedinstead of didodecyl ethyl sulfonium ing this invention will now be described, and, 7s bromide.

Example VII that one-tenth mol of didodecyl ethyltelluronium chloride is used instead of didodecyl ethyl sulionium bromide.

Each of the above-described modifled clay products forms a gel in an organic liquid and has a substantial gel-forming characteristic therein in the manner heretofore defined. In all of these the onium base has at least ten carbon atoms.

A material prepared as heretofore described will gel in oil, and 1 to 4% will produce a drilling fluid having the required viscosity and thlxotropic properties. Such a fluid may be prepared, using such proportions of the material as may be necessary to secure the desired properties. During the course of drilling, however, the material is added so as to maintain and control these properties.

Not only will the resultant drilling fluid have viscosity characteristics, but it will have thixotropic characteristics; both of which are desired, and even required, in.a drilling fluid. All oi this is accomplished in an oil phase, as distinguished from a water phase.

Having thus described the invention, what is claimed is:

1. An oil-base well-drilling fluid containing a modifled clay, originally exhibiting a substantial base-exchange capacity, in, which the clay cation has been replaced by a substituted cation of the class of onium bases consisting oi ammonium, phosphonium, suli'onium, arsonium, stibonium, oxonium and telluronium bases, and which forms a gel in the oil phase at the fluid and has a substantial gel characteristic therein to the extent that 2 grams 01 which modifled clay swell to at least 12 milliliters in nitrobenzene.

2. An oil-base well-drilling fluid containing a modifled clay, originally exhibiting a substantial base-exchange capacity, in which the clay cation has been replaced by a substituted cation of the class 01 onium bases consisting of ammonium, phosphonium, sulfonium, arsonium, stibonium, oxonium and telluronium bases, and in which the -oniumbasehasatleasttencarbonatoms.

3. An oil-base well-drilling fluid containing a modified clay, originally exhibiting a substantial base-exchange capacity; in which the clay cation has been replaced by a substituted onium ammonium base which forms a gel in the oil phase or the fluid and has a substantial gel characteristic therein to the extent that 2 grams of which mqdifledclay swell to at least 12 milliliters in nitrobenzene.

4. An oil-base well-drilling fluid containing a modified clay, originally exhibiting a substantial base-exchange capacity, in which the clay cation has been replaced by a substituted onium am- .monium base which has at least ten carbon atoms.

5. An oil-base well-drilling fluid containing a modified montmorillonite in which the replaceable cation of the clay mineral has been replaced by a substituted cation of the class of onium bases consisting of ammonium, phosphonium, sulionium, arsonium, stibonium, oxonium and telluronium bases, which forms a gel in the oil phase 01 the fluid and has a substantial gel characteristic therein to the extent that 2 grams of which modified clay swells to at least.12 milliliters in nitrobenzene.

6, An oil-base well-drilling fluid containing a modified montmorillonite in which the replaceable cation oi. the clay mineral has been replaced by a substituted cation 01' the class of onium bases consisting of ammonium, phosphonium, su1- Ionium, arsonium, stibonium, oxonium and telluronium bases, and in which the onium base has at least ten carbon atoms.

ERNST A. HAUSER.

REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS Number Name Date 1,991,637 Harth Feb. 19, 1935 2,033,856 Smith Mar. 11, 1936 2,055,666 Moore et a1. Sept. 29, 1936 2,217,926 Van Campen Oct. 15, 1940 2,259,875 Bent et a1 Oct. 21, 1941 2,248,636 Marsden July 8, 1941 2,360,544 Bond Oct. 17, 1944 

1. AN OIL-BASE WELL-DRILLING FLUID CONTAINING A MODIFIED CLAY, ORIGINALLY EXHIBITING A SUBSTANIAL BASE-EXCHANGE CAPACITY, IN WHICH THE CLAY CATION HAS BEEN REPLACED BY A SUBSTITUTED CATION OF THE CLASS OF ONIUM BASES CONSISTING OF AMMONIUM, PHOSOPHONIUM, SULFONIUM, ARSONIUM, STIBONIUM, OXONIUM AND TELLURONIUM BASES, AND WHICH FORMS A GEL IN THE OIL PHASE OF THE FLUID AND HAS A SUBSTANTIAL GEL CHARACTERISTIC THEREIN TO THE EXTENT THAT 2 GRAMS OF WHICH MODIFIED CLAY SWELL TO AT LEAST 12 MILLILITERS IN NITROBENZENE. 